WO2008043906A2

WO2008043906A2 - Intervertebral stabilization assembly

Info

Publication number: WO2008043906A2
Application number: PCT/FR2007/001638
Authority: WO
Inventors: Henry Graf
Original assignee: Henry Graf
Priority date: 2006-10-06
Filing date: 2007-10-08
Publication date: 2008-04-17
Also published as: FR2913329B3; WO2008043906A3; FR2913329A1

Abstract

This stabilization assembly comprises: at least one extradiscal element (40, 40', 50, 50'), especially of the plate type, arranged behind the intervertebral space and able to limit a movement between two adjacent vertebrae at least in the direction of intervertebral flexion; and at least one elastic member (42), which can be compressed upon lordosis of said two adjacent vertebrae in such a way as to control this lordosis.

Description

INTERVERTEBRAL STABILIZATION ASSEMBLY

The present invention relates to an intervertebral stabilization assembly. The invention is in the field of arthrodesis, namely bone fusion between at least two adjacent vertebrae. Already known intervertebral stabilization elements, which comprise at least one extradiscal displacement limiting element, plate type. This extra-discal element is able to limit a displacement between two adjacent vertebrae, in the direction of the intervertebral flexion.

Such a plate, making it possible to limit the intervertebral flexion, is for example described in US Pat. No. 4,743,260. Once this plate has been put in place, its tensioning force induces an approximation effort of the intraosseous implants, in particular back of the center of rotation of the two vertebrae. This approximation in turn causes a tensioning of the previous disc elements and enhances the articular facets totally or partially preserved, which forms the basis of the therapeutic stability thus reconstituted by the effect of guying.

This plate, which provides a guy function, provides a three-dimensional stabilization of the joint, initially destabilized by the degradation of the disc. It provides osteosynthesis to promote intervertebral fusion, by adding an appropriate bone graft. This known solution, however, has certain disadvantages since it does not satisfactorily take into account the degeneration of the intervertebral disc. In particular, this solution does not allow not a good adaptation to the different types of degradation of this disc.

That being said, the invention aims to remedy these various disadvantages. For this purpose, it relates to an intervertebral stabilization assembly according to claim 1 attached.

The invention will be described below, with reference to the accompanying drawings, given solely by way of non-limiting example, in which:

- Figures 1 and 2 are schematic views, respectively side and back, illustrating three neighboring vertebrae associated with an intervertebral stabilization assembly according to the invention; FIG. 3 is a side view illustrating on a larger scale an elastic element of this stabilization assembly; Figure 4 is a perspective view, illustrating an alternative embodiment of this elastic element;

- Figure 5 is a rear view, illustrating an alternative embodiment of the invention;

- Figure 6 is a side view, illustrating another embodiment of the invention; FIGS. 7A to 7C illustrate three stages of the installation of an intervertebral stabilization assembly, according to a further variant embodiment of the invention;

- Figure 8 is a side view, similar in particular to Figures 7A to 7C, illustrating a further embodiment of the invention;

Fig. 9 is a rear view illustrating the intervertebral stabilization assembly shown in Fig. 8; Figures 10 and 11 are perspective views illustrating two alternative embodiments of the resilient member belonging to the stabilizing assembly of Figures 8 and 9; and FIGS. 12 and 13 are respectively side and perspective views, illustrating two additional embodiments of this elastic member.

Figures 1 and 2 illustrate three adjacent vertebrae 10, 20 and 30 which are connected through a stabilization assembly according to the invention, which will be described in more detail in the following. Each vertebra comprises a respective vertebral body 12, 22, 32, two pedicles 14, 14 ', 24, 24' and 34, 34 ', and a posterior arch 16, 26, 36.

In a manner known per se, each pedicle is associated with a respective pedicle screw 18, 18 ', 28, 28', 38 and 38 ', which is implanted by any appropriate procedure. On either side of the sagittal axis A of the patient, there are various plates of a type known per se, which are for example in accordance with the teaching of US-A-4,743,260.

More specifically, a first plate 40 connects the pedicle screws 18 and 18 ', while a second plate 40' connects the pedicle screws 18 'and 28', within a first intervertebral stage. In addition, two additional plates 50 and 50 'intervene at the level of the adjacent intervertebral stage, respectively connecting the screws 28 and 38, as well as 28' and 38 '.

In the example illustrated, extra-disc elements are shown in the form of plates. However, as a variant not shown, it is possible to use any type of extra-disc element articulated with respect to the implanted screw, which provides a stay function, so as to limit a movement between the adjacent vertebrae, at the less in the direction of intervertebral flexion. Under these conditions, it is possible to use in particular a plate having a different shape, or even an inextensible ring, open or closed, total or partial. One can still use a rod or bar articulated at both ends, which is made of a metal material, plastic, composite, or any suitable biocompatible material.

Advantageously, the extra-disc element has a proper shape, which means that it is likely to keep the same geometry in the absence of external constraints, especially under the effect of gravity alone. In addition, the geometry of this extra-discal element does not vary substantially during the usual constraints to which it is subjected, once implanted on the patient. In this perspective, this plate can be completely rigid. However, it may have a slight flexibility, similar to that described in US-A-4,743,260. An elastic pad 42 is interposed between the posterior arches 16 and 26 of the two adjacent vertebrae 10 and 20. It is made of any suitable material, to ensure this elastic function. Thus, it can be formed from a single material, for example of the polymer type, or be made of a composite material. In the figures, there is shown a single pad 42. However, it is of course possible to use another similar pad, intended to be crushed between the posterior arches 26 and 36. As shown more particularly in Figure 3, this pad 42, of generally cylindrical shape, is crushed between the two posterior arches 16 and 26 in a neutral standing position of the patient. In these conditions, because of its elastic nature, it is suitable for oppose the hyper-lordosis of the patient, as will be seen in what follows.

Furthermore, the pad 42 is provided with connecting means relative to the two plates 40 and 40 'which are adjacent thereto. Thus, in FIGS. 1 to 3, this pad 42 has an elastic body 44, as well as a rigid core 46, metal or plastic, which is provided at its two ends with loops 48 and 48 'in which the respective plates. Alternatively, as shown in Figure 4, the core 146 of the pad 142 may be terminated by two forks 148, 148 'providing the same function as the aforementioned loops.

It will be noted that these connection means 48 and 48 ', however, allow a clearance between the pad 42 and the plates 40, 40', according to the main direction of the latter, which is substantially parallel to the sagittal axis.

A. In other words, the pad and each plate are slidable relative to each other along the main axis of this plate. On the other hand, these connecting means ensure a hooking of this pad with respect to these plates, which limits the deflection along a transverse axis, in this case horizontal in FIG. 2. The presence of these connecting means allows a maintaining the pad 42 between the posterior arches 16 and 26, which avoids any inadvertent separation, namely a possible forward migration in the channel or rearward, which would then remove any role to this pad. It will be noted that the pad 42 can not perform a satisfactory function, apart from its association with an inter-pedicle stay, such as the plates 40 and 40 '. This is explained not only by the physical connection between the pad and the plates, but also and especially because the stabilization deficiencies of the pad alone are large, given the importance of degenerative disc destabilization. This pad therefore needs to be associated with the plates to ensure true three-dimensional intervertebral stability. In this respect, it will be noted that the use of a single pad would position the vertebrae in kyphosis with respect to each other, which is not physiological since standing position at rest corresponds to a quasi-lordosis. complete.

The operation of the intervertebral stabilization assembly, described above with reference to Figures 1 to 3, will now be explained in what follows.

During the kyphosis of the patient according to the arrow Di, the various plates play their role in the usual way, namely that they oppose intervertebral flexion. For this purpose, they exert an action materialized by the arrows Fi. During this movement, it should be noted that the pad 42 does not intervene substantially. These plates 40 may be called "guy plates", in English "voltage-plates".

Advantageously, the action of the plates, shown by the arrows Fi, is a so-called firm voltage. In other words, when the plate plays its role of stay, it generates a tension to prevent intervertebral flexion, without however being subjected to significant elongation. Therefore, during this tensioning by the plate, the distance between the pedicle screws of two adjacent vertebral stages does not vary substantially. This is to be compared with extra-disc elements formed for example by braiding, which are subject to substantial elongation during their tensioning. Note also that, in the latter case, it is not necessary to provide connecting means 48 and 48 ', such as those described above. Indeed, since there is no significant variation in the distance between the pedicle screws, the pad 42 is set up stably. Thus, the maintenance of this interspinous pad does not need ligament or other lacing with the spinous processes, nor other means of stability, since its stability depends on its firm and constant crushing due to the shrouds arranged on the part and else.

Then, when setting lordosis, materialized by the arrow D ₂ , the pad 42 is crushed. Under these conditions, because of its elastic nature, it exerts a force materialized by the arrows F ₂ which tends to limit the amplitude of this lordosis, to avoid setting hyper-lordosis of the patient (see in particular Figure 3 where the plate is partially torn off). During this phase, the plates do not play a significant role.

The combination between the plates and the pad is advantageous, especially in comparison with the prior art involving plates alone.

Indeed, the pad forms a posterior element, adapted to elastically limit the amplitude of lordosis that could exert the plate alone. As a result, the use of this pad makes it possible to protect the facets with regard to too great a compression, or even an osteoarthritic evolution. In addition, this pad prevents compression of the nerve root in the foramen, due to a setting lordosis too important through the plates.

It should also be noted that, since the plate and the pad are independent members, their stiffness and / or elasticity can be adjusted independently. This is particularly advantageous, since such an adjustment makes it possible to adapt to the different types of degeneracy of the disc.

In this respect, it will be recalled that the disk is likely to undergo a degenerative collapse which may be symmetrical, but also asymmetrical. Thus, it is likely to collapse forward in the direction of kyphosis, ^" either backwards in the direction of lordosis, or laterally towards one or the other side, and / or any combination of these components together.

However, it is the merit of the Applicant to have highlighted that the shrouds used in isolation, in the state of the art, do not properly take into account the evolution of the degeneration of the intervertebral disc, especially its too great flexibility or its too great stiffness, or its total collapse, according to the evolutionary stage and / or the biogenetic conditions which preside over its degradation. Therefore, with a single stay, the same force is applied without nuance or possibility of adaptation. Under these conditions, this known solution does not allow a good adaptation to the different types of degradation of the disc, presented above.

On the other hand, the present invention provides a satisfactory solution for adapting to these different types of degradation.

Thus, if the disk collapses in kyphosis, it will be to accentuate the guying effect of the plate and, possibly, to reduce the mechanical strength of the pad. On the other hand, if the collapse occurs in lordosis, one will use a less firm cable-stayed and a pad offering more mechanical resistance. It is also possible to vary the thickness of this pad, in order to possibly increase the amount of matter of this pad to be compressed, according to the malposition in lordosis or pre-existing kyphosis.

In addition, if the disc collapses laterally asymmetrically, it will be possible to use struts more or less stretched, at the same intervertebral stage, and a pad that can be optionally thicker and / or more resistant on the side where this collapse takes place.

FIG. 5 illustrates a further variant embodiment of the invention. This embodiment finds its application in the case where the posterior arches of the adjacent vertebrae have been destroyed, because of the disease or the surgery. Under these conditions, the use of a pad, intended to be crushed between these arches, can not be envisaged in a simple way.

Thus, in FIG. 5, there is an elastic member 52 which consists of two prestressed spring blades 54, 54 'connected by a central rod 56. Each spring blade 54 and 54', which has an overall shape of Ω, is supported by its free ends 55, 55 'against the facing pedicle screws 18 and 18', as well as 28 and 28 ', belonging to two adjacent vertebral stages. In this figure 5, the different plates are not shown.

The implementation of the elastic member 52 is similar to that of the pad 42. Thus, during the lordosis of the patient, the two leaf springs 54, 54 'oppose such movement, according to the arrows F of It will be noted that, as a variant, it is possible to use two prestressed spring blades 54 and 54 'which are dissociated, ie which are not connected by a central rod 56. It will also be noted that the stiffnesses of the two blades 54 and 54 'may be different, especially in the case of a lateral dissymmetrical collapse of the disk. Finally, note that it is possible to use a single elastic blade 54 or 54 ', provided on one side of the intervertebral stage. In this regard, it will be understood that the or each leaf spring is not intended to work alone, because it might otherwise dislodge during the patient's movements. Therefore, it finds its stability and its mechanical balance, as well as its maintenance in good position only with the association of the stay, as the plate described in the example that comes to cover the blade spring back and forces it to maintain in cooperation position with the retainer implanted in the bone.

FIG. 6 illustrates a further variant of embodiment that can be used also in the case where the posterior vertebral arches are destroyed. There is thus a member 62, extending between two adjacent vertebral stages, which comprises a central elastic body 64, made for example of elastomer. This body is extended by two forks 66 intended to cover the heads of the adjacent pedicle screws 18 and 28. As shown in FIG. 6, the elastic member 62 is thus disposed in the vicinity of a plate 40.

It is possible to provide another elastic member, similar to that 62, between the two other pedicle screws of the same intervertebral stage. In a manner analogous to that described with reference to FIG. 5, the elasticities of these two members, equipping the same intervertebral stage, can be adjusted independently according to the conditions of degeneration of the disc.

It will be noted that the various elastic members 42, 52 and 62, described in the preceding figures, are held in place by means of the action of the stays. Under these conditions, it is not necessary to provide a complex fixation of these elastic members on the vertebral area, but only a link relatively simple relative to either adjacent stays or adjacent pedicle screws.

Figures 1Α to 7C illustrate a further variant embodiment of the invention. This variant is more particularly its application in the case where the intervertebral device has undergone a very sensitive collapse. This situation is illustrated in FIG. 7A, where it can be seen that the adjacent vertebral bodies 12 and 22 are considerably closer together, resulting in a large decrease in the volume of the intervertebral space E.

In this embodiment, it firstly uses a flexible body 100 whose function is to ensure the filling of this intervertebral space. Such a flexible member is for example made of a silicone-type elastomer or a composite material. Such a flexible member is deformable, while being substantially non-compressible.

Under these conditions, it is first of all to introduce this flexible body in the intra-disc space E by any appropriate means, as shown in Figure 7B, which ensures a filling of the cavity of the degenerative disc. This fill, type stuffing, is intended to allow the extension of the disc cavity under pressure, so as to put in tension all the peripheral elements of the disc, and in particular the hinge anterior 11. Moreover, this operation s 'accompanied by a release of the lateral foramens and the nerve root they surround, which induces a spacer effect, of the' spacer 'type.

Once the flexible body 100 in place, it is then possible to implant the pedicle screws, shrouds and the or each elastic pad (not shown in Figures 7), as described above. We therefore finds an association of three elements. Firstly, spacing and pressurization of a cavity that is still partially closed but collapsed, then a rear closure by guying so as to obtain the lordosis necessary for the intra-discal imprisonment of the flexible body, as well as a good erect position of the patient.

The use of the flexible body 100 is particularly advantageous, especially in the case of a disc that has collapsed very significantly. Indeed, in the absence of such a flexible body, this collapse would make very difficult the guying provided by the plate, which would no longer manage to lordose the joint to stabilize it. In other words, the establishment of a plate in the absence of the flexible body 100 would require applying a very high tension of guying, which would generate additional mechanical stresses on the facets, foramens already shrunk, as well as on the pedicle screws. The introduction of the flexible body 100 in the intra-disc cavity first ensures a filling of the latter, which again guarantees an acceptable intervertebral height, for the purpose of setting up the stays. Note that the posterior bracing, provided by the plates, finds its stability by re-tensioning all the intervertebral ligamentary elements remained intact, while bearing on the intra-discal flexible organ in a three-point type system. The use of this flexible member also has the advantage of absorbing shocks and vibrations.

Finally, note that the main function of the flexible body 100 is to ensure a filling of the extradiscal space, and the pressurization of this space as in the physiology of the disc where this pressure is of type hydraulics, creating the necessary spacing effect for therapy. Since this flexible body is deformable, it is likely to switch to lordosis by responding to the mechanical stresses of the posterior guying, especially for osteosynthesis respecting the balance of a biped erect position.

In these conditions, the structure of this flexible body is much simpler than that of a partial or total disc prosthesis, which generally includes components of different natures, which are animated by friction, sources of wear. In addition, the placement of these prostheses requires surgery by anterior route, with destruction of the peripheral ligaments, in particular of the anterior hinge, which are the only elements of residual stability in this degenerative context.

Figures 8 to 11 illustrate a further variant of the intervertebral stabilization assembly according to the invention. The embodiment of these figures 8 to 11 differs from those of the preceding figures, essentially in that the elastic member capable of being crushed during the setting in lordosis, is not extra-discal but now intra-discal. Thus, with reference to FIG. 8, this intra-discal elastic member is a spring blade 242, C-shaped, which has a core 242i provided opposite the plate 40, namely in the vicinity of the anterior hinge 11 This soul is extended by two wings 2422, each bearing against a respective vertebral body 12 or 22. This leaf spring 242 and has an open end 242 ₃ , facing the back of the patient, namely that it is adjacent to the plate 40. The material constituting this leaf spring 242 is similar, for example, to that in which are formed the leaf springs 54 and 54 '. It can thus be expected to use any suitable bio-compatible material, or a composite material.

The operation of the intervertebral stabilization assembly, illustrated in this FIG. 8, is generally similar to that of the stabilization assemblies of the preceding figures. It will first be noted that the leaf spring 242 provides an intervertebral spacing function. Because of its elastic nature, it is furthermore able to deform under the effect of a constraint and then to return to its initial configuration when this constraint is removed.

During the lordosis of the patient, the stress thus exerted tends to deform this elastic spring blade 242, by mutual approximation of the wings 242 ₂ . This blade then exerts a restoring force, embodied by the arrows G in FIG. 8. As a result, it opposes a permanent "counter-stress" elastic to the extradiscal stay 40.

Moreover, when returning to the neutral position of the patient or his kyphosis setting, the plate plays its usual role, while the leaf spring ensures only its function of intervertebral retractor, without however substantially deform. It will be appreciated therefore that the intervertebral stabilization assembly of the invention provides different functions, depending on the point of application of the patient's gravity forces.

Thus, if the patient leans forward, the posterior stay confines the kyphosis setting, while distributing the forces on the intra-discal implant 242, without the height of the latter decreases. In other words, this implant 242 continues to perform its function of intervertebral spacing.

When the patient leans back, he elastically deforms and resists spring blade 242, until the deformation in lordosis finds its counterpart in elastic resistance from this blade. A point of equilibrium between the forces applied is then reached. In this respect, it will be noted that the presence of the open end 242 ₃ , turned towards the plate, ensures a preferential deformation of this spring blade during the setting in lordosis.

The intra-discal implant 242 thus performs a dual function, namely firstly the intervertebral spacing, a "spacer" effect and, secondly, the setting in intervertebral lordosis due to its asymmetrical anterior distortion. later. Due to the nature of this implant 242 and the stay 40, an equilibrium is obtained between the mechanical effects of these two components, which corresponds to the therapeutic neutral position. As in the case of the pad 42 or the elastic member 52, it is possible to adjust the mechanical characteristics of the leaf spring 242, independently of those of the stay 40. It can also be provided with reference to FIG. use two leaf springs 242a and 242b, placed on either side of the sagittal axis A of the patient.

As in the case of spring blades 54 and 54 'of Figure 5, the use of these two leaf springs 242a and 242b is advantageous. Indeed, it is possible to separately adjust the mechanical characteristics of these two leaf springs, in order to take into account a possible lateral dissymmetrical collapse of the disk.

FIG. 10 illustrates an alternative embodiment of the spring blade, in which the latter is associated with a secondary spring 243, connecting the opposite wings 242 '2- Thus, during the deformation of the leaf spring 242' due to the lordosis of the patient, the spring 243 opposes a controlled intensity resistance. In this respect, it will be noted that it is possible to vary the mechanical characteristics of this spring 243, as a function of the pathology that is to be treated, and in particular if the collapse of the disc is asymmetrical of right-left type. As a variant not shown, the spring 243 can be replaced by a spring blade, similar to that 242 ', which has smaller dimensions and a lower resistance.

FIG. 11 illustrates a further variant embodiment of the intra-disc resilient member of FIGS. 8 to 10. In this embodiment, the spring blade 242 is replaced by a solid body 242 '', which also generally has a C shape. , which is provided with a core 242 _X '' from which extend two wings 242 ₂ ''. The soul is dug a notch 244, allowing the deformation of this massive body in the manner of a clothespin.

FIG. 12 illustrates a further variant embodiment of the intra-disc elastic member. The latter, affected in its entirety by the reference 342, differs from that 242 of FIG. 8 in that it comprises a non-deformable rigid body 345, made for example in the form of a cylindrical axis, extending transversely. This rigid body 345, which is fixed by any appropriate means against the core 342i of the spring blade 342, makes it possible to maintain substantially constant the height of this blade 342, at least in the vicinity of this body 345, whatever the level of imposed constraint. Under these conditions, this blade 342 is able to reliably ensure its intervertebral spacing function. In this regard, it should be noted that this elastic member 342 can be divided into two regions. The first region 342A, located at the front, ie opposite the plate. 40, is substantially rigid with respect to a vertical compression force, so that it more particularly provides the intervertebral spacing function. Moreover, the second region 342B, facing the plate 40, is adapted to be crushed during the setting in lordosis, while offering a controlled resistance as was explained in this

10 above.

Note that the rigid body 345 can equip the implant of Figures 10 and 11. In particular, in the case of Figure 11, it can be housed in the notch 244.

Referring to Figure 9, we note that the

Two spring blades 242a and 242b are placed substantially parallel to each other, on either side of the sagittal axis A. However, as a variant, it is possible for these two spring blades to be placed obliquely, in order to form overall views

20. a V, the tip of which is turned forward, ie opposite the plate 40.

As a further variant, illustrated in FIG. 13, these two spring blades can be grouped into a single intra-disc elastic member, designated in its

442. The latter firstly comprises a median rigid body 445, for example made in the form of a sphere, providing the effect of spacing, in a similar manner to the rigid body 345 of FIG. 12.

This rigid body 445 is for example placed at

Near the sagittal axis A of the patient. In addition, two pairs of elastic wings 442 ₂ i and 442 ₂₂ extend from the median body 445, namely on either side of the sagittal axis A, respectively to the left and to the right of it. this. Thus, seen from above, the elastic member 442 has a shape of V, the tip is turned forward.

Each pair of wings 442 ₂ i and 442 ₂₂ is of elastic and deformable nature, so that they provide a resistance to guying, similarly for example to the wings 242 ₂ equipping the implant of Figure 8. As in the case of Figure 9, we can predict that these two pairs of wings have different mechanical characteristics, so as to oppose variable resistances, especially in the case of a dissymmetrical lateral collapse of the disc.

Claims

An intervertebral stabilization assembly for connecting at least two adjacent vertebrae (10, 20, 30), comprising:

at least one extra-disc displacement limiting element (40, 40 ', 50, 50'), in particular of the plate type, intended to be disposed behind the intervertebral space, which is capable of limiting a displacement between two adjacent vertebrae at least in the direction of intervertebral flexion; and

at least one elastic member (42; 52; 62; 142; 242; 242a; 242b; 242 '; 242 "; 342; 442), independent of the extra-disc displacement limiting element, which is suitable for being crushed during the lordosis of said two adjacent vertebrae, so as to control this setting in lordosis.

2. An assembly according to claim 1, characterized in that the elastic member (42; 52; 62; 142) is extradiscal.

3. An assembly according to claim 2, characterized in that the or each extra-discal elastic member is a transverse member (42; 142) adapted to be crushed between the vertebral posterior arches (16, 26, 36) during said setting. in lordosis.

4. An assembly according to claim 3, characterized in that there are provided connecting means (48, 48 '; 148, 148'), in particular removable, between the elastic transverse member (42; 142) and the or each extra-disc element (40, 40 ', 50, 50') of displacement limitation.

5. The assembly of claim 4, characterized in that the connecting means are hooking means (48, 48 ', 148, 148'), adapted to allow sliding relative to the extra-discal displacement limiting element (40, 40 ', 50, 50') and the elastic transverse member (42; 142), in the longitudinal direction of this extra-disc element, while limiting the displacement of the elastic transverse member relative to the extra-discal displacement limiting element, transversely to the main direction of the latter.

6. An assembly according to claim 2, characterized in that the or each extra-disc elastic member (52; 62) is adapted to bear against at least two retaining members, in particular pedicular screws (18, 18 ', 28, 28 '), belonging to two adjacent vertebral stages.

7. An assembly according to claim 6, characterized in that the or each extra-disc elastic member (52) is formed as a prestressed spring blade (54, 54 ') adapted to bear, by its free ends (55 , 55 '), against the retainers.

8. An assembly according to claim 6, characterized in that the or each extra-disc elastic member (62) comprises a resilient central body (64), extended by two connecting ends (66), for example in the form of a fork, clean to cooperate with the adjoining retainers.

9. Assembly according to any one of the preceding claims, characterized in that said stabilization assembly further comprises a flexible body (100), intended to be placed in the intra-disc space (E), so as to fill this latest.

10. The assembly of claim 9, characterized in that the flexible body is deformable, while being substantially not compressible.

11. The assembly of claim 1, characterized in that the elastic member (242; 242a, 242b; 242 '; 242 ", 342, 442) is intra-discal and further provides an intervertebral spacing function.

12. The assembly of claim 11, characterized in that the intra-disc elastic member (242; 242a, 242b; 242 '; 242 "; 342) has an open end (242 ₃ ) of preferential deformation during the implementation. lordosis of the patient.

13. The assembly of claim 12, characterized in that the intra-disc elastic member (242; 242a, 242b; 242 '; 242 "; 342) has a generally C-shape, seen from the side.

14. The assembly of claim 13, characterized in that the intra-discal elastic member C-shaped (242 ') has deformation limiting means, in particular a secondary spring (243) extending between the wings facing of this elastic member (242 ').

15. Assembly according to any one of claims 12 to 14, characterized in that the intra-disc elastic member (242; 242a, 242b; 242 '; 342) is formed as a spring blade.

16. The assembly of claim 11 or 12, characterized in that the intra-disc elastic member comprises a median body (445), from which extend two pairs of deformable wings (442 ₂ i, 442 ₂₂ ), this elastic member having generally a V-shape, seen from above.

17. Assembly according to any one of claims 11 to 16, characterized in that the intra-disc elastic member (342; 442) is provided with a rigid body (345; 445) for maintaining the intervertebral spacing, this rigid body being provided at the front, namely the opposite of the extra-discal displacement limiting element (40).

18. Assembly according to any one of the preceding claims, characterized in that the extra-discal element (40, 40 ', 50, 50') is able to prevent any displacement between two adjacent vertebrae in the direction of the intervertebral flexion. .

19. The assembly of claim 18, characterized in that the extra-discal element is adapted to generate a voltage, to prevent movement between two adjacent vertebrae, without significant change in the distance between the pedicle screws connected by this extra-disc element.

20. An assembly according to any one of the preceding claims, characterized in that the extra-disc displacement limiting element has a body having a shape of its own.

21. Assembly according to any one of the preceding claims, characterized in that, for at least one vertebral stage, at least one first extra-disc element (40, 50) and at least one second extra-disc element ( 40 ', 50') intended to be implanted on either side of the sagittal axis (A) of the patient, as well as at least one first elastic member (54; 242a) and at least one second elastic member ( 54 '242b) intended to be placed on either side of said sagittal axis, the stiffness and / or elasticity of said extra-disc elements and said elastic members can be adjusted independently.